0314495 JOHNSON CLAMP, Distributor base

Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
110-3 Engine Coolant Temperature Sensor voltage above normal The engine Electronic Control Module (ECM) detects signal voltage that is more than 4.95 VDC for 8 seconds.
The ECM has been powered for at least 2 seconds. The code is logged if the engine has been running for more than 7 minutes. The ECM uses the last valid engine coolant temperature. If the diagnostic code is active at start-up, the ECM will use intake manifold temperature. If intake manifold air temperature is not valid, the ECM will default to 90 °C (194 °F) for engine coolant temperature. The ECM will activate the cooling fan after this code has been active for more than 8 seconds.
110-4 Engine Coolant Temperature Sensor voltage below normal The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds.
The ECM has been powered for at least 2seconds.
172-3 Intake Manifold Air Temperature Sensor voltage above normal The engine ECM detects signal voltage that is more than 4.95 VDC for 8 seconds.
The ECM has been powered for at least 2 seconds. The ECM will log the diagnostic code. The ECM will flag the intake manifold air temperature as invalid data and the intake manifold air temperature is set to a default value of 40 °C (104 °F).
172-4 Intake Manifold Air Temperature Sensor voltage below normal The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds.
The ECM has been powered for at least 2seconds.
174-3 Fuel Temperature Sensor voltage above normal The engine Electronic Control Module (ECM) detects signal voltage that is more than 4.95 VDC for 8 seconds.
The ECM has been powered for at least 2 seconds. The code is logged. The ECM will flag the fuel temperature as invalid data and the fuel temperature is set to a default value of 40 °C (104 °F).
174-4 Fuel Temperature Sensor voltage below normal The ECM detects signal voltage that is less than 0.2 VDC for 2 seconds.
The ECM has been powered for at least 2 seconds.
2526-3
Air Inlet Temperature Sensor : Voltage Above Normal The engine Electronic Control Module (ECM) detects signal voltage that is more than 4.95 VDC for 8 seconds.
The ECM has been powered for at least 2 seconds. The code is logged. The ECM detects voltage that is not in the acceptable range.
2526-4
Air Inlet Temperature Sensor : Voltage Below Normal The ECM detects signal voltage that is less than 0.2 VDC for 2 seconds.
The ECM has been powered for at least 2 seconds. The code is logged. The ECM detects voltage that is not in the acceptable range. System OperationUse this procedure to troubleshoot any suspect problems with the following sensors:
Coolant temperature sensor
Intake manifold air temperature sensor
Fuel temperature sensor
Air inlet temperatureThe sensor signal for the passive sensor is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the passive sensors is routed from the ECM to terminal 2 of each sensor connector.
Illustration 1 g02165060
Schematic for the passive analog sensors
Illustration 2 g02165062
Terminal locations at the P2 ECM connector for the engine temperature sensors
(P2-17) Analog sensor return
(P2-83) Analog sensor return
(P2-84) Engine coolant temperature
(P2-95) Intake manifold air temperature
(P2-96) Fuel temperature
Illustration 3 g01423043
Terminal locations at the connector for the passive analog sensors
(Terminal 1) Sensor signal
(Terminal 2) Analog sensor return
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Remove electrical power from the ECM.
B. Connect Caterpillar Electronic Technician (ET) to the service tool connector.
C. Restore electrical power to the ECM.
D. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
E. Determine if a diagnostic code has occurred several times.
Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection between a socket and a pin in a connector or of a poor connection between a wire and a terminal.
F. Determine if the problem is active and related to one of the following diagnostic codes:
• -3
• -4
G. Remove electrical power from the ECM.
Codes
Result: A diagnostic code is not active.
Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
Result: An active -3 diagnostic code is present.
Proceed to Test Step 2.
Result: An active -4 diagnostic code is present.
Proceed to Test Step 4.
2. Check for Battery Voltage on the Signal Wire
A. Restore electrical power to the ECM.
B. Measure the voltage on the harness side of the sensor connector between pin 1 and engine ground for the suspect sensor.
C. Remove electrical power from the ECM.
Battery Voltage
Result: The signal voltage is less than battery voltage.
Proceed to Test Step 3.
Result: The signal voltage is equal to battery voltage.
Repair: There is a short circuit to battery voltage in the harness. Repair the wiring harness or replace the wiring harness.
STOP
3. Create a Short Circuit at the Connector for the Suspect Sensor
A. Disconnect the suspect sensor.
B. Fabricate a jumper wire that is long enough to create a test circuit across the harness side of the sensor connector. Crimp connector pins to each end of the jumper wire.
C. Install the jumper wire between terminal 1 (sensor signal) and terminal 2 (sensor return) at the sensor connector.
D. Restore electrical power to the ECM.
E. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -4 diagnostic code for the suspect sensor.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
F. Remove electrical power from the ECM.
.
Short Circuit
Result: A -3 diagnostic code was active before creating the short at the sensor connector. A -4 diagnostic code became active after creating the short at the sensor connector. The wiring between the ECM and the sensor connector is OK.
Repair: Temporarily connect a new sensor to the harness, but do not